With less than 24 hours before Christmas, 40-year-old Mira begged her parents to flee their hometown of Aleppo, which has become a major battleground in Syria's civil war.

Her parents refused to join her in Lebanon, but they are taking one simple precaution inside their besieged city. For the first time, Mira says, her parents will not put up a Christmas tree this year for fear their religion might make them a target.

"They want to stay to guard the property so nobody takes it," said Mira, who spoke to The Associated Press in Lebanon on condition that only her first name be published, out of concern for her family.

"They cannot celebrate Christmas properly. It's not safe. They are in a Christian area, but they don't feel secure to put a tree, even inside their apartment," Mira said.

Christians, who make up about 10 per cent of Syria's population of more than 22 million, say they are particularly vulnerable to the violence that has been sweeping the country since March 2011. They are fearful that Syria will become another Iraq, with Christians caught in the crossfire between rival Islamic groups.

Hundreds of thousands of Christians fled Iraq after their community and others were targeted by militants in the chaotic years after dictator Saddam Hussein was ousted in 2003.